'Belief in QS' has often been used to represent the assertion that for the purposes of evaluating utility the probability assigned to events should only take into account worlds where survival occurs. In that mode of thinking, 'the probability of experiencing injury' is what I would describe as p(injury | survival).

In this sense I don't believe in QS. BTW, I don't think you can believe in the correctness of utility functions. You can believe in the correctness of theories and then you decide your utility function. It may be even inconsistent (and you can be money pumped), still that's your choice, based on the evidences.

It makes sense to first split the following three components:

• Mathematical questions (In this specific case, these are very basic probability theoretical calculations)
• (Meta-)physical questions: Is the MWI correct? Is mangled world correct? etc. Do our consciousness continues in all Everett branches? etc.
• Moral questions: What should you choose as a utility function assuming certain physical theories

It seems that you try to mix these different aspects.

If you notice the necessity to revise your calculations or physical world view, then it may force you to update your moral preferences, objective functions as well. But you should never let your moral preferences determine the outcome of your mathematical calculation or confidence in physical theories.